This invention relates generally to slide viewing apparatus, and more particularly to an automatic advertising device for displaying images on a screen.
In recent years there has been a tremendous growth in surburban shopping centers and in many cities a reduction in the downtown shopping. Many shopping centers or malls have been developed that have become little cities unto themselves with many different stores sharing a common roof and mall area. There has developed a need for a type of advertising medium that can be utilized in shopping malls, which will expose customers to advertisements of specially priced leader items to induce the customers to shop in a store. Numerous attempts have been made in the past to develop projection display devices for use in advertising. Known U.S. Patents relating to projection devices are as follows: U.S. Pat. Nos. 472,912; 737,940; 1,089,788; 1,107,293; 1,535,131; 1,812,547; 1,870,301; 2,250,297; 2,405,706; 2,461,756; 2,570,652; 2,618,119; 3,072,015; 3,322,035; 3,421,802. Many such projectors such as U.S. Pat. No. 1,812,547 issued to Nowack, et al, disclose a slide carrying rotating disc 4, a drive mechanism 10, including ratchet star 7 which engages another ratchet star 6 to rotate the slide carrying disc in increments to align a transparency with a light and lens. The image projected through the lens is reflected from a mirror 18 onto a screen 19. Another type of projecting device is shown in U.S. Pat. No. 1,089,788 to Quigley. The Quigley device is similar to the device of Nowack, et al, and further includes a shutter means to avoid exposure of portions of a receding picture and an approaching picture.
In order to be commercially feasible, it is necessary that a slide viewing apparatus used for advertising purposes be very simple in construction to minimize the number of moving parts and also to minimize any required maintenance. It is important that such devices be able to operate over extended periods of time without any maintenance other than the changing of slides to reflect additional items for sale. It is also important that the device be simple and inexpensive to manufacture to make it economically feasible for use by a merchant.